Shear claw bit

ABSTRACT

A shear claw drill bit includes a bit body and a plurality of pick receptacles fixedly attached to the bit body. Each pick receptacle has a pick cavity. The shear claw drill bit further includes a plurality of picks. Each pick has a cutter cavity. The shear claw drill bit also includes a plurality of polycrystalline diamond compact (PDC) cutters. Each PDC cutter is disposed in the cutter cavity of a respective pick of the plurality of picks. A portion of each PDC cutter protrudes out of the cutter cavity of the respective pick.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. Section 119(e)to U.S. Provisional Patent Application No. 61/885,772, titled “ShearClaw Bit,” filed Oct. 2, 2013, the entire disclosure of which isincorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates generally to downhole tools used insubterranean drilling, and more particularly, to shear claw drill bits.

BACKGROUND

Drill bits are commonly used for drilling into earth formations. Shearcutter polycrystalline diamond compact (PDC) drill bits are among themore commonly used types of drill bits. Typical PDC drill bits arebladed, and arrays of PDC cutters are disposed along the blades. The PDCcutters are typically brazed in cutter pockets formed in the blades,where the cutters are not filed replaceable. When PDC drill bits gothrough a complete rotation, a full bottom hole coverage is typicallyachieved because of a significant overlap of the PDC cutters in arotational projection of the PDC cutters. In general, shear cutter PDCbits are extremely efficient at shearing rocks. Typically, cuttingsgenerated along a given blade face of a PDC bit slide along the bladeface to exit from the bit face of the PDC drill bit. In some cases, thecuttings may cause erosion and abrasion of the bit and may also damagethe bit due to unwanted regrinding of the cuttings. In someapplications, PDC bits may also experience off-center rotation due totorque moment generation along each blade.

Claw-type point attack bits are also among the more commonly used bittypes. Typical claw-type point attack bits are used extensively in softsoil industrial applications such as mining. Typically, cutting picksare mounted into machined sockets in the bit body in such a way that thecutting pick are free to rotate. Because the tip of the a cutting pickis typically separated from the bit body by the shaft of the cuttingpick and the sockets, cutting picks of claw-type point attack bitsbenefit from fluid flow around the cutting picks. In general, claw-typepoint attack bits do not have full bottom hole coverage in a rotationalprojection. Although, such full or near full bottom hole coverage isgenerally not a requirement in the typical application of claw-typepoint attack bits in soft rock formations, use of such claw-type pointattack bits in harder formations may not be efficient.

Accordingly, a drill bit with a shear claw configuration that providesfor efficient fluid flow around the cutters while providing a relativelywider bottom hole coverage in a rotational projection is desirable.

SUMMARY

The present disclosure relates generally to downhole tools used insubterranean drilling, and more particularly, to shear claw drill bits.In some example embodiments, a shear claw drill bit includes a bit bodyand a plurality of pick receptacles fixedly attached to the bit body.Each pick receptacle has a pick cavity. The shear claw drill bit furtherincludes a plurality of picks. Each pick has a cutter cavity, where eachpick is disposed in the pick cavity of a respective pick receptacle ofthe plurality of pick receptacles. The shear claw drill bit alsoincludes a plurality of polycrystalline diamond compact (PDC) cutters.Each PDC cutter is disposed in the cutter cavity of a respective pick ofthe plurality of picks. A portion of each PDC cutter protrudes out ofthe cutter cavity of the respective pick.

In another example embodiment, a method of fabricating a shear clawdrill bit includes attaching pick receptacles to a bit body. The pickshave pick cavities. The method further includes placing picks in thepick cavities. The picks have cutter cavities. The picks are removablyattached to the pick receptacles. The method also includes placingcutters in the cutter cavities and attaching the cutters to the pickswithin the cutter cavities.

In another example embodiment, a shear claw drill bit includes a bitbody having a bit face. The shear claw drill bit further includes aplurality of columns extending out from the bit face. The plurality ofcolumns have cutter cavities that are distal from the bit face. The bitbody and the plurality of columns are made from a single structure. Theshear claw drill bit also includes a plurality of cutters disposed inthe cutter cavities, where a portion of each cutter of the plurality ofcutters protrudes out of a cutter cavity.

In yet another example embodiment, a method of fabricating a shear clawdrill bit includes carving out columns from a steel structure such thatthe columns protrude out from a portion of the steel structure, wherethe portion of the steel structure defines a bit body of the shear clawdrill bit. The method further includes removing column portions of thecolumns to form cutter cavities in the columns. The cutter cavities aredistal from the bit body. The method also includes placing cutters inthe cutter cavities and attaching the cutters placed in the cuttercavities to the columns.

These and other aspects, objects, features, and embodiments will beapparent from the following description and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will now be made to the accompanying drawings, which are notnecessarily drawn to scale, and wherein:

FIG. 1 is a perspective view of a shear claw drill bit according to anexample embodiment;

FIGS. 2A and 2B are cross-sectional views of a cutter-carrying pickdisposed in the pick receptacle of the shear claw drill bit of FIG. 1according to an example embodiment;

FIG. 3 is a cross-sectional view of a cutter-carrying pick disposed inthe pick receptacle of the shear claw drill bit of FIG. 1 according toanother example embodiment;

FIG. 4 is a cross-sectional view of a cutter-carrying pick disposed inthe pick receptacle of the shear claw drill bit of FIG. 1 according toanother example embodiment;

FIG. 5 is a perspective view of a shear claw drill bit according toanother example embodiment;

FIGS. 6A and 6B are top and profile views of a steel structure used tomake a bit body and columns of a shear claw drill bit such as the shearclaw drill bit of FIG. 5 according to an example embodiment;

FIG. 7 illustrates a first set of illustrative cut patterns that can bemade in the steel structure of FIGS. 6A and 6B during the process ofmaking a shear claw drill bit according to an example embodiment;

FIG. 8 illustrates a second set of illustrative cut patterns that can bemade in the steel structure of FIGS. 6A and 6B following the cutpatterns shown in FIG. 7 or instead of the cut patterns shown in FIG. 7according to an example embodiment;

FIG. 9A illustrates columns formed by carving the steel structure ofFIGS. 6A and 6B according to an example embodiment;

FIG. 9B illustrates example columns orientations that can be formed bycarving the steel structure of FIGS. 6A and 6B according to an exampleembodiment;

FIG. 10 illustrates nozzle holes located in the bit face shown in FIG.9A according to an example embodiment;

FIG. 11 illustrates cutter cavities formed in the columns according toan example embodiment; and

FIG. 12 illustrates cutters disposed in the cutter cavities shown inFIG. 11 according to an example embodiment.

The drawings illustrate only exemplary embodiments of the invention andare therefore not to be considered limiting of its scope, as theinvention may admit to other equally effective embodiments.

DETAILED DESCRIPTION OF THE INVENTION

The present disclosure is directed to downhole tools used insubterranean drilling. In particular, the present disclosure relates toshear claw drill bits that provide a high degree bottom hole coverage ina rotational projection of the cutters and improved flow area forcuttings to exit from a bottom hole. The present disclosure may bebetter understood by reading the following description of non-limiting,example embodiments with reference to the attached drawings, whereinlike parts of each of the figures are identified by like referencecharacters, and which are briefly described as follows.

FIG. 1 is a perspective view of a shear claw drill bit 100 according toan example embodiment. The shear claw drill bit 100 includes a bit body102 and a threaded connector 104 attached to the bit body 102. The shearclaw drill bit 100 further includes pick receptacles 108 and picks 110that are positioned in the pick receptacles 108. For example, the pickreceptacles 108 may be welded to the bit face of the bit body 102. Insome example embodiments, the pick receptacles 108 may be slanted, forexample, 45 degrees relative to a horizontal plane. Alternatively, thepick receptacles 108 may be slanted less or more than 45 degreesrelative to the horizontal plane.

In some example embodiments, a number of the pick receptacles 108 may beattached to the bit body 106 proximal to the outer perimeter of the bitface 106 and may be in a generally round configuration. Other pickreceptacles 108 may be attached to the bit body 106 in the interior ofthe bit face and may be in a round or other configuration.

The picks 110 are disposed in the pick receptacles 108. For example, aportion of a shaft of the pick 110 may be positioned within the pickcavity of the pick receptacle 108, and another portion of the shaft ofthe pick 110 may protrude out from the pick receptacle 108 asillustrated in FIG. 1. In general, each pick receptacle 108 has one pickcavity, where one pick 110 is disposed in the pick cavity of the pickreceptacle 108.

In some example embodiments, the picks 110 may be removably attached tothe pick receptacles 108. For example, the picks 110 may be fieldreplaceable to allow replacement of worn out or damaged picks or toallow replacement for other reasons. The picks 110 may also berotationally fixed within the pick cavities of the pick receptacles 108.To illustrate, the pick 110 may be positioned within the pick cavity ofthe pick receptacle 108 such that the pick 110 does not rotate relativeto the pick receptacle 108.

As illustrated in FIG. 1, the shear claw drill bit 100 includes cutters112 that are attached to the picks 110. For example, the cutters 112 maybe PDC cutters, for example, ranging in diameter from 8 millimeter (mm)to 22 mm. The cutters 112 are attached to the picks 110 at the endportion of the picks 110 distal from the bit body 102. As more clearlyshown in FIGS. 2A-4, each cutter 112 may be positioned in a cuttercavity of the picks 110. For example, the cutters 112 may be fixedlyattached to the picks 110 within the cutter cavities formed in the picks110 by brazing or similar methods. A cutter cavity may be machined(e.g., drilled) into the picks 110 to have a shape and a size that allowa cutter (e.g., a PDC cutter) to be positioned in the cutter cavity. Forexample, the cutter cavities may have a round cross-section with adiameter that is slightly larger than a diameter of a particular PDCcutter.

In some example embodiments, each cutter 112 may have a sloped cuttingsurface such that the cutter 112 has a non-zero rake angle. For example,the cutters 112 may have a rake angle of approximately 20 degrees. Toillustrate, one side of the cutter 112 may protrude out from the cuttercavity more than an opposite side of the cutter 112.

In some example embodiments, one or more of the picks 110 may includetwo or more cutter cavities such that two or more cutters are attachedto the picks 110. For example, two cutters 112 may be attached to eachof the picks 110 or some of the picks 110. To illustrate, some of thepicks 110 may carry one cutter 112, and the remaining picks 110 maycarry two or more cutters 112. For example, the cutters 112 attached thepick 110 that carries two or more cutters 112 may be smaller than thecutters 112 attached to the picks 110 that carry one cutter 112. Two ormore cutters 112 attached to the single pick 110 may oriented in thesame direction and may have the same rake angle.

In some example embodiments, the shear claw drill bit 100 includesnozzles openings 114 in the bit face 106 of the bit body 102. The nozzleopening 114 are used for providing drilling fluid during drillingoperations.

In some example embodiments, the threaded connector 104 of the shearclaw drill bit 100 may be coupled to a drill string (not shown) or someother equipment that is coupled to a drill string. The threadedconnector 104 as shown in FIG. 1 is threaded on the exterior surface ofthe threaded connector 104. In some alternative embodiments, thethreaded connector 104 may be threaded in the interior surface of thethreaded connector 104 for a connection with an externally threadedconnector of a drill string or other equipment.

The shear claw drill bit 100 may utilize picks 110 that carry one ormore shear cutters 112 (e.g., shear PDC cutters) on an end portion ofeach pick distal from the bit body 102. In contrast to the typicalmining pick tips of claw drill bits, the distal end portion of each pick110 is significantly wider to provide one or more cutter cavities forcorresponding one or more shear cutters. Further, because each pick 110is rotationally fixed (e.g., keyed) with respect to the respective pickreceptacle 108, the cutting edge of the shear cutter (e.g., the shearPDC cutter) remains in place to cut the preferred location along thebottom hole profile.

In contrast to typical claw-type point attack bits, the rotationalprojection of the cutters 112 may provide a much wider bottom holecoverage. For example, in some example embodiments, the rotationalprojection of the cutters 112 may provide a full or near full bottomhole coverage. Further, because the cutters 112 are disposed at thedistal ends of the picks 110, cuttings generated during drillingoperations may exit from the bit face 110 without causing excessiveerosion or abrasion to the shear claw drill bit 100. Further, incontrast to bladed PDC bits, the cutters 112 (e.g., PDC cutters) may bereplaced in the field by replacing the picks 110, which results in timeand cost savings when cutters need to be replaced during drillingoperations.

In some example embodiments, the bit body 102, the pick receptacles 108,and the picks 210 may be made from steel using methods known to those ofordinary skill in the art with the benefit of this disclosure. Asdescribed above, the cutters 112 may be PDC cutters.

In some example embodiments, the shear claw drill bit 100 may have feweror more pick receptacles 108 than shown in FIG. 1. The pick receptacles108 may also be positioned in a different configuration and/or locationsthan shown in FIG. 1. Further, the shear claw drill bit 100 may have adifferent shape than shown in FIG. 1, without departing from the scopeof this disclosure.

Example uses of the shear claw drill bit 100 include oil and gas PDCbits, blast hole mining PDC bits, horizontal directional diamond (HDD)PDC bits, and underground tunneling raise bore machines.

FIGS. 2A and 2B are cross-sectional views of a cutter-carrying pick 202disposed in the pick receptacle 108 of the shear claw drill bit 100 ofFIG. 1 according to an example embodiment. The pick 202 is disposed in apick cavity 214 of the pick receptacle 108. A PDC cutter 204 is disposedin a cutter cavity 212 of the pick 202. In some example embodiments, thepick 202 and the PDC cutter 204 may be used with the shear claw drillbit 100 of FIG. 1 in place of the pick 110 and the cutter 112,respectively.

As illustrated in FIGS. 2A and 2B, the pick 202 is positioned in thepick receptacle 108. The pick receptacle 108 may be machined (e.g.,drilled) to form the pick cavity 214 that is shaped and sized to receivethe pick 202. To illustrate, a portion of the pick 202 may be within thepick cavity 214, and another portion of the pick 202 may protrudeoutside of the pick cavity 214 as illustrated in FIG. 2A. The pick 202may be removably attached to the pick receptacle 108 such that the pick202 is field replaceable.

The cutter cavity 212 may be formed in the pick 202 by machining out(e.g., drilling) a portion of the pick 202 at an end portion of the pick202 that is distal from a bottom wall 210 of the pick receptacle 108.The PDC cutter 204 may be positioned in the cutter cavity 212 and may befixedly attach to the pick 202 by brazing. The PDC cutter 204 may have adiameter ranging from 8 mm to 22 mm.

In some example embodiments, the bottom wall 210 of the pick receptacle108 may be welded to the bit body 102. Alternatively or in addition, theside walls of the pick receptacle 108 may be welded to the bit body 102.In some example embodiments, a portion of or the entire bottom wall ofthe pick receptacle 108 may be omitted such that the pick 202 protrudesout or is accessible at the bottom end of the pick receptacle 108.

In some example embodiments, the pick receptacle 108 includes protrudingkeying structures 206 that may be inserted into key receptors 208 formedin the pick 202 to prevent the pick 202 from rotating within the pickcavity 214. Alternatively, the pick 202, instead of the pick receptacle108, may include keying structures that are inserted into key receptorsformed in the pick receptacle 108. The keying structure 206 and the keyreceptor 208 allow the pick 202 to be field replaceable while preventingthe pick 202 from rotating within the pick cavity 214 during drillingoperations. In some example embodiments, other structures may be usedinstead of or in addition to the keying structures 206 and the keyreceptors 208 to prevent the pick 202 from rotating within the pickcavity 214 without departing from the scope of this disclosure.

As illustrated in FIGS. 2A and 2B, a portion of the PDC cutter 204 mayprotrude out from the cutter cavity 212. In FIG. 2A, a cutting edge 216of the PDC cutter 204 protrudes out from the cutter cavity 214 such thatthe cutting surface 218 of the PDC cutter is slightly backraked relativeto the horizontal plane 220 in the orientation shown in FIG. 2A. Toillustrate, the PDC cutter 204 may have a non-zero rake angle. Forexample, the PDC cutter 204 may have a rake angle of 20 degrees.Alternatively, the PDC cutter 204 may have a rake angle that is greateror less than 20 degrees. To illustrate, the PDC cutter 204 has a largerrake angle n FIG. 2B than in FIG. 2A. For example, the rake angle of thePDC cutter 204 as shown in FIG. 2B may be approximately 40 degrees.

Although the cutting surface 218 of the PDC cutter 204 is sloped asshown in FIGS. 2A and 2B, in some alternative embodiments, the PDCcutter 204 may protrude out from the cutter cavity 214, where thecutting surface 218 is not sloped. Further, in some example embodiments,the pick 202 may protrude out from the cavity less or more than shown inFIGS. 2A and 2B.

FIG. 3 is a cross-sectional view of a cutter-carrying pick 302 disposedin the pick receptacle of the shear claw drill bit of FIG. 1 accordingto another example embodiment. The pick 302 is disposed in the pickcavity (i.e., the pick cavity 214 described with respect to FIG. 2A) ofthe pick receptacle 108. A PDC cutter 304 is disposed in a cutter cavity312 of the pick 302. In some example embodiments, the pick 302 and thePDC cutter 304 may be used with the shear claw drill bit 100 of FIG. 1in place of the pick 110 and the cutter 112, respectively. Toillustrate, the pick receptacle 108 shown in FIG. 3 may be the same asthe pick receptacle 108 of FIG. 1.

Similar to the PDC cutter 204 shown FIGS. 2A and 2B, the PDC cutter 304may be slightly backraked. For example, the PDC cutter 304 may have anon-zero (e.g., 20 degrees) rake angle.

As illustrated in FIG. 3, the pick 302 may include a shank 306 and anend portion 308 that is wider than the shank 306. The cutter cavity 312may be formed in the end portion 308 of the pick 302 by drilling and/orother means known to those of ordinary skill in the art with the benefitof this disclosure. The PDC cutter 304 disposed in the cutter cavity 312may be larger than the PDC cuter 204 in the shear claw drill bit 100shown in FIGS. 2A and 2B. To attach the PDC cutter 304 with the pick302, the PDC cutter 304 may be positioned in the cutter cavity 312 andmay be brazed to the pick 302. The PDC cutter 304 may have a diameterranging from 8 mm to 22 mm.

The pick 302 may be made as a single structure or may be made byattaching the shank 306 and the end portion 308 together using methodssuch as welding. For example, the pick 302 may be made from steel orother similar materials. As described with respect to the pick 110 ofFIG. 1 and the pick 202 of FIGS. 2A and 2B, the pick 302 is removablyattached to the pick receptacle 108, which enables field replacement ofthe pick 302 for reasons such as when the pick 302 or the PDC cutter 304being worn or damaged.

FIG. 4 is a cross-sectional view of a cutter-carrying pick 402 disposedin the pick receptacle of the shear claw drill bit of FIG. 1 accordingto another example embodiment. The pick 402 is disposed in the pickcavity (i.e., the pick cavity 214 described with respect to FIG. 2A) ofthe pick receptacle 108. PDC cutters 404 are disposed in cutter cavities412 of the pick 402. In some example embodiments, the pick 402 and thePDC cutters 404 may be used with the shear claw drill bit 100 shown inFIG. 1 in place of the pick 110 and the cutter 112, respectively. Toillustrate, the pick receptacle 108 shown in FIG. 4 may be the same asthe pick receptacle 108 of FIG. 1.

Similar to the PDC cutter 204 shown FIGS. 2A, 2B, and 3, the PDC cutters404 may be slightly backraked. For example, each one of the PDC cutters404 may have a non-zero rake angle. For example, both PDC cutters 404may have substantially the same rake angle (e.g., approximately 20degrees). Alternatively, the PDC cutters 404 may have different rakeangles.

As illustrated in FIG. 4, the pick 402 may include a shank 406 and anend portion 408 that is wider than the shank 406. The cutter cavity 412may be formed in the end portion 408 of the pick 402 by drilling and/orother means known to those of ordinary skill in the art with the benefitof this disclosure. For example, the PDC cutters 404 may be smaller thanthe PDC cuter 204 shown in FIGS. 2A and 2B and the PDC cutter 304 shownin FIG. 3. To attach the PDC cutters 404 with the pick 402, the PDCcutters 404 may be positioned in the cutter cavities 412 and may bebrazed to the pick 402. Each PDC cutter 404 may have a diameter rangingfrom 8 mm to 22 mm.

Similar to the pick 302 of FIG. 3, the pick 402 may be made as a singlestructure or may be made by attaching the shank 406 and the end portion408 together using methods such as welding. For example, the pick 402may be made from steel or other similar materials. As described above,the pick 402 may be removably attached to the pick receptacle 108, whichenables field replacement of the pick 402 for reasons such as when thepick 402 or the PDC cutters 404 being worn or damaged.

FIG. 5 is a perspective view of a shear claw drill bit 500 according toanother example embodiment. The shear claw drill bit 500 includes a bitbody 502 and columns 510. The bit body 502 includes a bit shank 504. Athreaded connector 506 may extend down from the bit shank 504 in theorientation of the shear claw drill bit 500 shown in FIG. 5. The columns510 extending out from the bit face 508 of the bit body 502. The shearclaw drill bit 500 further includes cutters (e.g., a PDC cutter) 512disposed in cutter cavities formed at the end portions of the columnsdistal from the bit face 508 of the bit body 502.

The bit body 502 and the columns 510 are parts of a monolithic structuremade from a singular structure such as a steel structure. As explainedfurther below, the columns 510 may be machined out of a singular steelstructure. In some example embodiments, the columns 510 may bedistributed on the bit face 508 in the configuration shown in FIG. 5.For example, the columns 510 may be evenly distributed around the bitface 508. Alternatively, the columns 510 may be unevenly distributedaround the bit face 508. To illustrate, the columns 510 may bedistributed around the bit face 508 in a configuration that allows for afull or near full bottom hole coverage by the shear claw drill bit 500.Further, the columns 510 may be distributed around the bit face 508 in aconfiguration that also provides room for cuttings to travel between thecolumns 510. For example, the columns 510 may be spaced to provideadequate room between the columns 510 for cuttings to travel withoutexcessive damage to the bit body 502 or the columns 510.

As illustrated in FIG. 5, in some example embodiments, each column 510carries one cutter 512. A cutter cavity may be machined (e.g., drilled)into each column 510 at an end portion of the column 510 distal from thebit face 508 of the bit body 502. The cutters 512 are disposed in thecutter cavities of the columns 510 machined into the columns 510. Forexample, the cutters 512 may be brazed with the columns 510 within thecutter cavities.

In some example embodiments, one or more of the columns 510 may have twoor more cutter cavities at the end portion of the columns 510 distalfrom the bit face 508. For example, one or more of the columns 510 maycarry two of the cutters 512. To illustrate, one cutter 512 may bedisposed in one cutter cavity of one column 510, and another cutter 512may be disposed in another cutter cavity of the same column 510. As yetanother example, one or more of the columns 510 may carry three of thecutters 512. To illustrate, some of the columns 510 may be wider thanother columns 510 to accommodate more cutter cavities and more cutters512. Alternatively, all of the columns 510 may have substantially thesame width, where some of the columns 510 carry more cutters 512 thanother columns 510.

In some example embodiments, the columns 510 may be substantiallyperpendicular to the bit face 508. For example, when the bit face 508 issubstantially flat and generally in a horizontal plane, the columns 510may extend in a substantially vertical direction as viewed in theorientation of the shear claw drill bit 500 shown in FIG. 5. In somealternative embodiments, one or more of the columns 510 may benon-perpendicular to the bit face 508. For example, one or more of thecolumns 510 may protrude out from the bit face 508 in a non-verticalangle.

In some example embodiments, each column 510 may extend out at least 3inches from the bit face 508. For example, some or all of the columns510 may extend out approximately 3.5 inches from the bit face 508. Ingeneral, the columns 510 may extend out from the bit face 508 to provideadequate room for cuttings to travel between the columns 510. Toillustrate, the columns 510 may extend out from the bit face 508 toprovide adequate room for cuttings exit the bit face 508 withoutexcessive damage to the bit body 502 or the columns 510. For example,the columns 510 may have thicknesses that minimize risks of breakageduring drilling operations.

In some example embodiments, each cutter 512 may range in diameter insize from 8 mm to 22 mm. For example, the cutters 512 of the shear clawdrill bit 500 may all have the same size or may have different sizes.

As illustrated in FIG. 5, the cutters 512 extend beyond the columns 510.For example, a portion of each cutter 512 may protrude out of the cuttercavity of the respective column 510. For example, the cutters 512 may beslightly backraked to have a desired rake angle. In general, the cutters512 may have a non-zero rake angle (e.g., 20 degrees).

In some example embodiments, the shear claw drill bit 500 includesnozzles openings 514 in the bit face 508 of the bit body 502. The nozzleopening 514 are used for providing drilling fluid during drillingoperations. The shear claw drill bit 500 may also include junk slots 516that facilitate efficient travel of cuttings away from the bit face 508.In some example embodiments, the junk slots 516 may be evenlydistributed around the bit body 502. The junk slots 516 may be formed inthe bit body using methods known to those of ordinary skill in the art.

In some example embodiments, the threaded connector 506 of the shearclaw drill bit 500 may be coupled to a drill string (not shown) or someother equipment that is coupled to a drill string. In general, thethreaded connector 504 corresponds to the threaded connector 104 shownin FIG. 1 and may be used in a similar manner.

In contrast to some bladed PDC bits, the shear claw drill bit 500provides for increased room between the cutters 512 and the bit body 502for cuttings to travel away from the bit face 508, which reduces therisk of excessive damage to the bit body 502 and to the columns 510.Further, by distribution the columns 510 on the bit face 508 in somedesired configurations, the shear claw drill bit 500 may provide full ornear full bottom hole coverage in a rotational projection of the cutters512, which allows for efficient drilling. The use of shear PDC cuttersas the cutters 512 also allows the shear claw drill bit 500 to be usedfor drilling in hard formations.

In some example embodiments, the shear claw drill bit 100 may have feweror more columns 510 than shown in FIG. 5. Further, some or all of thecolumns 510 may have shapes other than shown in FIG. 5 without departingfrom the scope of this disclosure. Further, the shear claw drill bit 500may have a different shape than shown in FIG. 5 without departing fromthe scope of this disclosure. In some example embodiments, some of thecolumns 510 may be formed on the gage sides of the bit body 102.

Example uses of the shear claw drill bit 500 include oil and gas PDCbits, blast hole mining PDC bits, horizontal directional diamond (HDD)PDC bits, and underground tunneling raise bore machines.

FIGS. 6A and 6B are top and profile views of a steel structure 600 usedto make a bit body and columns of a shear claw drill bit such as theshear claw drill bit of FIG. 5 according to an example embodiment. FIG.6A illustrates a top view of the steel structure 600, and FIG. 6Billustrates a side profile view of the steel structure 600. For example,the steel structure 600 may be a machined or cast steel structure. Toillustrate, the steel structure 600 may be die casted to have thegeneral outline of the shear claw drill bit 500 of FIG. 5. The steelstructure 600 may also be made by a combination of die casting andmachining (e.g., carving) using various tools such as drills.

To make a shear claw drill bit such as the shear claw drill bit 500, abit designer may first determine the desired location of PDC cutters onthe bit face of the planned shear claw drill bit, and then design plungecuts to be made in the top surface 602 of the steel structure 600 thatwill leave steel columns in the desired locations.

In some alternative embodiments, a structure made from a material otherthan steel may be used instead of the steel structure 600. Further, insome embodiments, the steel structure 600 may have a shape other thanshown in FIGS. 6A and 6B without departing from the scope of thisdisclosure. For example, the top surface 602 may have be flatter thanshown in FIG. 6B without departing from the scope of this disclosure.

FIG. 7 illustrates a first set of illustrative cut patterns 702 can bemade in the steel structure 600 of FIGS. 6A and 6B during the process ofmaking a shear claw drill bit according to an example embodiment. Forexample, the steel structure 600 may be carved using carving tools toform steel columns. To illustrate, drills and/or end mills (e.g., narrowdiameter end mills) may be used to plunge deeply into the top surface602 of the steel structure 600 to begin to define the steel columns,which will carry the PDC cutters. For example, end mills that areapproximately 1 inch may be used alone or in combination with a drill(s)to make the cut patterns 702 or other cut patterns in the steelstructure 600. In some example embodiments, cut patterns may also bemade in the gage side 604 of the steel column 600 shown in FIG. 6B.

The cut patterns 702 are illustrative and other cut patterns may be madein the steel body 600 to define the planned steel columns withoutdeparting from the scope this disclosure. For example, fewer, smaller,or larger cuts than represented by the example cut patterns 702 may bemade in the steel body 600.

FIG. 8 illustrates a second set of illustrative cut patterns 802 can bemade in the steel structure 600 of FIGS. 6A and 6B according to anexample embodiment. For example, the second set of illustrative cutpatterns 802 or other cut patterns may be made after the example cutpatterns 802 shown in FIG. 7 are made or instead of the example cutpatterns 702. For example, after the first set of example cut patterns702 are made as shown in FIG. 7, drills and/or end mills may be used toplunge deeply into the remaining portions of the top surface 602 of thesteel structure 600 to continue to define the steel columns. In someexample embodiments, the cut patterns may also be made in the gage side604 of the steel column 600 shown in FIG. 6B.

Additional cut patterns may be made as needed plunge into the topsurface 602 of the steel structure 600 until the steel columns are welldefined. Additional cut patterns may also be made to define the bit faceof the planned shear claw drill bit. Once the primary cut patterns aremade by plunging into the steel body as described above, millingoperations can be performed to better define the steel columns. Forexample, jagged edges and rough surfaces of the steel columns can besmoothed as needed. The bit face may also be more clearly defined byperforming milling operations as needed. For example, curved edges ofthe bit face may be more clearly defined and smoothed as needed.

The cut patterns 802 are illustrative and other cut patterns may be madein the steel body 600 to define the planned steel columns withoutdeparting from the scope this disclosure. For example, fewer, smaller,or larger cuts than represented by the example cut patterns 802 may bemade in the steel body 600.

FIG. 9A illustrates columns 902 formed by carving the steel structure600 of FIGS. 6A and 6B according to an example embodiment. FIG. 9Billustrates example column orientations that can be formed by carvingthe steel structure 600 of FIGS. 6A and 6B according to an exampleembodiment. As illustrated in FIG. 9A, the columns 902 are distributedover a bit face 904 that is exposed after removal of portions the steelbody 600 to form the columns 902. Some of the columns 902 may havelarger surface dimensions than others. For example, surfaces of somecolumns 902 may be relatively long and/or wider than of some othercolumns 902.

As illustrated in FIG. 9A, some of the columns 902 may be substantiallyperpendicular to the bit face 904 while other columns 902 may beslanted. To illustrate, some of the columns 902 in FIG. 9A may beoriented similar to the column 906 of FIG. 9B such that the columns aresubstantially perpendicular to the bit face 904. Similarly, some columns902 in FIG. 9A may be slanted similar to the column 908 of FIG. 9B.Further, in some example embodiments, some of the columns 902 may beformed on the gage side 604 of the steel body 600 shown in FIG. 6Bsimilar to the column 910 of FIG. 9B.

Although a particular distribution of the columns 902 is shown in FIGS.9A and 9B, in alternative embodiments, the columns 902 may have adifferent configuration without departing from the scope of thisdisclosure. For example, the columns 902 may be distributed more or lessevenly on the bit face 904 than shown in FIG. 9A. Further, although thecolumns 902 are shown in FIG. 9A as having surfaces 912 that arerectangular, the surfaces 912 may have other shapes without departingfrom the scope of this disclosure. In general, the columns 902 may havethe surfaces 912 having other shapes including shapes with more or lessthan four sides without departing from the scope of this disclosure.Further, in some example embodiments, the edges of the surfaces 912 maynot be as smooth as shown in FIG. 9A. In general, some or all of thecolumns 902 may have shapes other than shown in FIG. 9A withoutdeparting from the scope of this disclosure.

FIG. 10 illustrates nozzle holes 1002 located in the bit face 904 shownin FIG. 9A according to an example embodiment. For example, long drillsand tap tools may be used to form the nozzle openings 1002 in the bitface 904 after the columns 902 are carved as described above. In someexample embodiments, more or fewer than the number of nozzle openings1002 shown in FIG. 10 may be formed in the bit face 904. Further, thenozzle openings 1002 may have a different configuration than shown inFIG. 10.

FIG. 11 illustrates cutter cavities 1102, 1104 formed in the columns 902according to an example embodiment. For example, some of the columns 902may have one cutter cavity 1102, and other columns 902 may have twocutter cavities 1104. In some alternative embodiments, some of thecolumns 902 may have more than two cutter cavities. The cutter cavities1102, 1104 may be machined/carved into the columns 902 at the endportion of each cutter 902 distal from the bit face 904. In some exampleembodiments, all of the columns 902 may have one cutter cavity 1102.Alternatively, all of the columns 902 may have two cutter cavities 1104.Some of the cutter cavities 1102 may be larger than the cutter cavities1104 to accommodate a larger cutter.

In some example embodiments, junk slots 1106 may also be formed. Thejunk slots facilitate efficient travel of cuttings away from the bitface 904. The junk slots 1106 may be formed by drilling or other methodsknown to those of ordinary skill in the art with the benefit of thisdisclosure.

FIG. 12 illustrates PDC cutters 1202, 1204 disposed in the cuttercavities 1102, 1104 shown in FIG. 11 according to an example embodiment.As illustrated in FIG. 12, one PDC cutter 1202 is positioned in some ofthe columns 902, and two PDC cutters 1204 are positioned in othercolumns 902. The PDC cutters 1202, 1204 may range in diameter from 8 mmto 22 mm. For example, the PDC cutters 1204 may be smaller than thecutters 1202. In some example embodiments, more than two PDC cutters(e.g., three PDC cutters 1204) may be positioned on some of the columns902.

The PDC cutters 1202, 1204 are attached to the columns 902 within thecorresponding cutter cavities 1102, 1104 of FIG. 11, for example, bybrazing. In general, the cutter cavities 1102, 1104 are slightly largerthan the PDC cutters 1202, 1204, respectively, to allow the PDC cutters1202, 1204 to be placed within the cutter cavities 1102, 1104.

Similar to the cutters 512 shown in FIG. 5, the PDC cutters 1202, 1204may protrude out of the cutter cavities 1102, 1104. Further, the PDCcutters 1202, 1204 may be slightly backraked similar to the cutters 512.The rotated profile of the PDC cutters 1202, 1204 may have full or nearfull bottom hole coverage, which allows for efficient drilling.

Nozzle sockets 1206 may be positioned in the nozzle openings 1002 shownin FIG. 10. The nozzle sockets 1206 are used for providing drillingfluid during drilling operations. In some example embodiments, thenozzle sockets 1206 may be positioned in the nozzle openings 1002 beforethe cutter cavities 1102, 1104 of FIG. 11 are formed. In general, someof the steps described with respect to FIGS. 6A-12 may be performed in adifferent sequence than described above.

As described above with respect to FIGS. 6A-12, shear claw drill bitssuch as the shear claw drill bit 500 may be made starting with a steelstructure (or another similar structure) and carving out the steelcolumns that carry cutters such as PDC cutters.

Although some embodiments have been described herein in detail, thedescriptions are by way of example. The features of the embodimentsdescribed herein are representative and, in alternative embodiments,certain features, elements, and/or steps may be added or omitted.Additionally, modifications to aspects of the embodiments describedherein may be made by those skilled in the art without departing fromthe spirit and scope of the following claims, the scope of which are tobe accorded the broadest interpretation so as to encompass modificationsand equivalent structures.

What is claimed is:
 1. A shear claw drill bit, comprising: a bit body; aplurality of pick receptacles fixedly attached to the bit body, whereineach pick receptacle has a pick cavity; a plurality of picks, whereineach pick is disposed in the pick cavity of a respective pick receptacleof the plurality of pick receptacles and wherein each pick has a cuttercavity; and a plurality of polycrystalline diamond compact (PDC)cutters, each PDC cutter disposed in the cutter cavity of a respectivepick of the plurality of picks, wherein a portion of each PDC cutterprotrudes out of the cutter cavity of the respective pick.
 2. The shearclaw drill bit of claim 1, wherein at least one pick of the plurality ofpicks has a second cutter cavity and wherein a second PDC cutter isdisposed in the second cutter cavity.
 3. The shear claw drill bit ofclaim 1, wherein each pick of the plurality of picks is removablysecured in the pick cavity of the respective pick receptacle.
 4. Theshear claw drill bit of claim 3, wherein each pick of the plurality ofpicks is rotationally fixed within the pick cavity of the respectivepick receptacle.
 5. The shear claw drill bit of claim 1, wherein eachPDC cutter of the plurality of PDC cutters is fixedly attached to therespective pick within the cutter cavity of the respective pick bybrazing the PDC cutter with the respective pick.
 6. The shear claw drillbit of claim 1, wherein the plurality of PDC cutters range in diameterfrom 8 millimeters (mm) to 22 mm.
 7. The shear claw drill bit of claim1, wherein the bit body, the plurality of pick receptacles, and theplurality of picks are made from steel.
 8. The shear claw drill bit ofclaim 1, wherein the plurality of pick receptacles are welded to the bitbody.
 9. The shear claw drill bit of claim 1, further comprising aplurality of nozzle opening in a bit face of the bit body.
 10. A methodof fabricating a shear claw drill bit, the method comprising: attachingpick receptacles to a bit body, the picks having pick cavities; placingpicks in the pick cavities, the picks having cutter cavities, whereinthe picks are removably attached to the pick receptacles; placing PDCcutters in the cutter cavities; and attaching the PDC cutters to thepicks within the cutter cavities.
 11. The method of claim 10, whereinattaching the pick receptacle to the bit body includes welding to thepick receptacles to the bit body.
 12. The method of claim 10, whereinattaching the PDC cutters to the picks includes brazing the PDC cutterswith the picks within the cutter cavities.
 13. The method of claim 10,wherein placing the PDC cutters in the cutter cavities includes placinga first PDC cutter in a first cutter cavity of a pick and placing asecond PDC cutter in a second cavity of the pick.
 14. The method ofclaim 10, wherein the picks are rotationally fixed within the pickcavities.
 15. A shear claw drill bit, comprising: a bit body having abit face; a plurality of columns extending out from the bit face, theplurality of columns having cutter cavities that are distal from the bitface, wherein the bit body and the plurality of columns are made from asingle structure; and a plurality of cutters disposed in the cuttercavities, wherein a portion of each cutter of the plurality of cuttersprotrudes out of a cutter cavity.
 16. The shear claw drill bit of claim15, wherein at least one column of the plurality of columns has a firstcutter cavity and a second cutter cavity, wherein a first cutter of theplurality of cutters is disposed in the first cutter cavity, and whereina second cutter of the plurality of cutters is disposed in the secondcutter cavity.
 17. The shear claw drill bit of claim 15, wherein thesingle structure is a steel structure and wherein the columns are carvedout from the steel structure.
 18. The shear claw drill bit of claim 15,wherein the cutter cavities are formed by drilling into an end portionof each column distal from the bit face.
 19. The shear claw drill bit ofclaim 15, wherein the plurality of cutters are polycrystalline diamondcompact (PDC) cutters.
 20. The shear claw drill bit of claim 19, whereinone or more cutters of the plurality of cutters has a non-zero degreerake angle.
 21. The shear claw drill bit of claim 15, wherein theplurality of cutters are brazed to the columns within the cuttercavities.
 22. The shear claw drill bit of claim 15, further comprisingnozzle openings in the bit face of the bit body.
 23. A method offabricating a shear claw drill bit, the method comprising: carving outcolumns from a steel structure such that the columns protrude out from aportion of the steel structure, the portion of the steel structuredefining a bit body of the shear claw drill bit; removing columnportions of the columns to form cutter cavities in the columns, thecutter cavities being distal from the bit body; placing cutters in thecutter cavities; and attaching the cutters placed in the cutter cavitiesto the columns.
 24. The method of claim 23, further comprising drillingnozzle holes into the bit body, wherein openings of the nozzle holes arelocated in the bit face.
 25. The method of claim 23, wherein removingthe column portions of the columns to form the cutter cavities in thecolumns includes forming a first cavity and a second cavity in at leastone of the columns, and wherein placing the cutters in the cuttercavities includes placing a first cutter in the first cutter cavity andplacing a second cutter in the second cutter cavity.
 26. The method ofclaim 23, wherein the cutters are polycrystalline diamond compact (PDC)cutters.
 27. The method of claim 26, wherein attaching the cutters tothe columns includes brazing the cutters to the columns.
 28. The methodof claim 23, wherein carving out the columns from the steel structureincludes using a drill to plunge into the steel body.